SCIENCE AND FAITH: THE HOMINID FOSSIL RECORD Lee A. Spencer, Ph.D. Earth History Research Center Southwestern Adventist University Keene, TX 76059 Abstract— The fossil hominids are bipedal primates with a mixture of great ape (pongid), human, and pongid-human intermediate character states. There is a morphological continuum in skull and skeletal morphologies spanning those seen in the chimpanzee and anatomically modern man. Evolutionary/theistic evolutionary, progressive creation and “young-earth” creation interpretations of the data set are examined and tested. No interpretation remains unfalsified. Any interpretation held requires the exercise of faith. Science and faith not only are possible together, they are required. 1 Introduction The cosmic questions of who we are and what our purpose in life is, if there is one, have been debated for as long as man has been in existence. So has the question of our origin. For millennia it has been commonly believed that a supernatural being or beings created man and this world. Over the last 150 years, this belief has been replaced by a naturalistic model in which man and this world came into being exclusively through naturally occurring processes. A conflict has ensued between those who believed in a supernatural being and those who do not. Few topics within the origins controversy engender more interest than that of man’s origin. Few topics better illustrate the intertwining of data and interpretation, science and faith, or cosmology and science. Associated with the origins controversy, there is intense debate about what is or is not science, what constitutes religion and faith and how these factors combine to produce our cosmology. Because there are widely differing views on exactly what constitutes each of these terms, this paper uses the following definitions: 1) Data are directly observable characters and measurements. For the discussion of human origins the data set would include observations and measurements of skeletal remains, descriptions of sedimentary context, various chemical constituents, etc. 2) Interpretations are conclusions drawn from the data. For example, based upon microscopic grooves on the teeth (data), dietary modes may be inferred; based upon a measured ratio of 40 K/ 40 Ar, the number of calendar years required to produce that ratio may be hypothesized, etc. Some interpretations may appear to be self-evident. Conversely, there may be different and opposing interpretations of the same data set. Often in the scientific literature, data and interpretation are so intermingled that it is difficult to determine the actual data set, or only the interpretations are reported. 3) Science is the process of formulating testable (i.e. rejectable) hypotheses about the natural world. 4) Faith is the acceptance of statements, interpretations and/or hypotheses as true in spite of the lack of data or even the presence of contradictory data. 5) Cosmology is the belief system explaining the cause for the underlying harmony in the universe. Examples of cosmologies include naturalism where natural law is self-existent and is the sole cause for the underlying harmony of the universe, and variations of supernaturalism where there is a being above natural law. Evolution is the extension of 2 naturalism that covers change through time. Theistic evolution, progressive creation, intelligent design, young earth creation, etc. are all variants of the supernaturalistic cosmology with differing levels or timings of intervention by the supernatural being. I know of no way to differentiate evolution and theistic evolution from observable data, so they will be treated together. Because cosmologies are belief systems, they are not directly testable and are hence outside the definition of science given above. It is not the purpose of this paper to resolve the cosmological debate on human origins, but to show how our understanding of what man is depends completely… not on the data, but upon previously adopted views that form a previously accepted cosmology. Further, the exercise of faith is required for all cosmologies. We will first examine the human origin data set very briefly, then examine interpretations and hypotheses of the three most prevalent cosmologies: evolution/theistic evolution, progressive creation and neodiluvialism/young-earth creation. A Summary of the Hominoid Data Set (Details, Details, Details) What Is A Hominid? Linnean classification places all the apes with man in the superfamily Hominoidea. The Hominoidea can be distinguished from all other primates in lacking a tail and in having a wrist design that allows greater wrist flexibility and greater dexterity of the hands and feet than other primates. The Hominoidea is divided into three families, the Hylobatidae (gibbons), the Pongidae (orangutan, gorilla, and chimpanzee), and the Hominidae (man). The three families are distinguished from each other by different modes of locomotion and the anatomical structures necessary for that type of locomotion. 3 The Hylobatidae (also known as the “lesser apes” or gibbons) are brachiators, which means that they move by swinging arm movements with the body hanging below the arms. The Pongidae or “great apes” are forelimb knuckle-walkers. The orangutan makes a fist and the first phalanx makes contact with the ground; the gorilla and chimpanzee use the second phalanx to make ground contact. The term “pongid” will be used throughout this paper to refer to this group. The Hominidae (human beings) walk habitually upright and the hands do not normally touch the ground. Upright walking primates are known as “hominids” from the family name Hominidae and modern man, Homo sapiens , is the only living representative. In the fossil record, there are a number of extinct, upright- walking primate taxa (hominids). The taxonomy of the fossil hominid specimens is hotly debated. Depending upon the author, there are nine to eighteen species placed within two to six genera. There is a general consensus, however, that all of the specimens can be placed within one of six general categories: the australopithecines, early “Homo”, the “erectines”, “archaic sapiens”, Neanderthals, and fully modern man. The australopithecines and early “Homo” are restricted to the African uppermost Miocene to Pliocene; the “erectines”, to the Old World Pliocene and Pleistocene; “archaic sapiens”, and Neanderthals to the Old World Pleistocene, and fully modern man to the Pleistocene and Holocene worldwide. 4 The classification of the hominid taxa used for this paper is modified from Tattersall (1993) and Wood and Collard (1999) and is as follows: Family Hominidae Insertae sedis Orrorin tugenensis Subfamily Australopithecinae Genus Ardipithecus Species Ardipithecus ramidus Genus Australopithecus Species Australopithecus anamensis Australopithecus afarensis Australopithecus africanus Australopithecus bahrelghazali (?) Genus undescribed Species “Homo” habilis Genus Paranthropus Species Paranthropus aethiopicus Paranthropus boisei Paranthropus robustus Paranthropus garhi Genus Kenyanthropus Species Kenyanthropus platyops Kenyanthropus rudolfensis Subfamily Homininae Genus Pithecanthropus Species Pithecanthropus erectus Pithecanthropus soloensis Genus Homo Species Homo heidelbergensis Homo neanderthalensis Homo sapiens Data Set I: Hominoid Skull Characters Living hominoids exhibit distinctly different skull morphologies. In the figure to the left is pictured an adult male gorilla skull. It can be characterized as having a prominent sagittal crest (ridge along the top of the skull), a large bony orbit (eye socket), and a prominent brow ridge. It also has a large flat facial area below the orbits and a protruding muzzle (prognathism) with large canine teeth. 5 Compared to the gorilla skull, the human skull lacks a saggital crest, has gracile orbits (thinner and smaller), and a short face, with no prognathism. There is no confusion about what is human and what is ape; there are no living morphologic intermediates. However, if the fossil hominids are included, a different picture emerges. A gradation of morphological characters is seen ranging from those features that are mostly gorilla and chimp-like to those that equal modern humans. Character states examined here include endocranial volume, various cranial features and facial structure, placement of the foramen magnum, and construction of the face, mouth and teeth. Endocranial Volume. Fully modern man has a brain capacity that averages about 1700 cc. The brain capacity of the pongids (gorilla, chimpanzee, orangutan) averages about 400 cc. There is no overlap between the smallest human brain capacity and the largest simian brain capacity. However, if we plot values including the fossil hominids, there is a gradation in endocranial volumes. 6 1. Pan sp. (chimpanzee), 2. Australopithecus africanus , 3. Pithecanthropus erectus , 4. Homo heidelbergensis , 5. H. neanderthalensis, 6. Anatomically modern man Cranial Morphology. Among the fossil hominids, we also see a gradation of cranial morphologies from an essentially pongid morphology to the modern human morphology. Large, bony eye sockets, a large nasal opening, and stout facial bones dominate the face of the pongid. The pongid facial pattern is seen in all fossil hominids except anatomically modern man. Chimpanzee Neanderthal Anatomically modern man Lateral View. A similar pattern is seen in lateral view. The pongid skull is characterized by a sulcus behind the brow ridges, prognathism and a protruding occipital region. Anatomically